The present invention relates to an improved process for the production of methyl, tertiary butyl ether. More particularly, the invention relates to an efficient methyl, tertiary butyl ether production process utilizing selected feedstocks.
Methyl, tertiary butyl ether (MTBE) is widely used, e.g., as a gasoline blending component. Typically, MTBE is produced via the etherification of isobutene with methanol. The isobutene is normally provided to the etherification step in a feedstock mixture containing substantial concentrations of butanes and n-butenes, as well as isobutene. For example, the feedstock can be the raffinate from a conventional extractive distillation recovering butadiene from the effluent of a conventional C.sub.4 dehydrogenation reactor system. Dienes and acetylenes are often present in the feedstock, particularly when it is derived from a dehydrogenation effluent.
The etherification reaction does not substantially convert the n-butenes. Straight chain olefins pass through the etherification system along with the butanes, dienes and acetylenes. Consideration has been given to isomerizing these residual n-butenes to isobutene and recycling the isomerate to etherification. However, the substantial build-up of butanes that would result in this recycle stream detrimentally affects the economics of such a processing option. Also, the presence of dienes and acetylenes in this recycle stream would be harmful to many of the isomerization catalysts that could be used to promote the n-butenes/isobutene isomerization.
The following reference materials have been reviewed in preparing this application: U.S. Pat. Nos. 4,329,516 and 4,555,312; Belgian Patent No. 887,125, and "The Changing Picture for C.sub.4 Feedstocks", Chemical Week, Dec. 16, 1981. These materials disclose producing MTBE and/or pure butene-1, and the varying market for the individual C.sub.4 hydrocarbons. There continues to be a need for an improved MTBE production process.
Accordingly, an object of this invention is to provide an improved process for the production of MTBE. Another object of the invention is to provide an MTBE production process with improved feedstock utilization and efficiency. More particular aspects, objects and the several advantages of this invention will become apparent to those skilled in the art upon reading this disclosure and the appended claims.